cpursley

PostgreSQL is Enough

• Simplify: move code into database functions
• Just Use Postgres for Everything
• Just use Postgres
• PostgreSQL is the worlds’ best database
• Postgres is eating the database world
• Hacker News discussion

Background and Cron Jobs

kconner

macOS Internals

Understand your Mac and iPhone more deeply by tracing the evolution of Mac OS X from prelease to Swift. John Siracusa delivers the details.

Starting Points

How to use this gist

You've got two main options:

VladimirReshetnikov

https://chat.openai.com/chat?model=gpt-4

User:

Propose a meaningful implementation of a Haskell function of type f :: (a → (Maybe a, b)) → a → [b]

---

ChatGPT:

peterstorm

{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE InstanceSigs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE StandaloneKindSignatures #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeFamilies #-}

Lysxia

{-# LANGUAGE
  DataKinds,
  DeriveGeneric,
  PolyKinds,
  StandaloneDeriving,
  TypeFamilies,
  UndecidableInstances #-}
module T where

import Data.Kind (Constraint, Type)

chrisdone-artificial

-- Written by Eitan Chatav, cleaned up by me

{-# language GADTs #-}

import Type.Reflection
import Data.Constraint

data U_Expr
  = U_Bool Bool
  | U_Int Int

chrisdone-artificial

{-

Examples:

> reify @Int $ eval $ A (reflect (abs :: Int -> Int)) (I (-9))
9

> reify @Int $ eval $ A (A (reflect ((*) :: Int -> Int -> Int)) (reflect @Int 3)) (reflect @Int 5)
15

rain-1

quick recap on complex numbers

Take a number, square it, the result is non-negative. Because positive * positive = positive and negative * negative is positive. Or $0^2 = 0^2$.

But someone wanted to take square roots of negative numbers, so they did, and called it 'i'. $\sqrt{-1} = i$. A lot of people were frustrated upon learning this "You can't do that!", "How do you know that it doesn't lead to contradictions".

The solution, to put imaginary and complex numbers on a solid foundation is something called a ring quotient. What you do is you start with the ring (meaning number system) of polynomials over the real numbers $R[i]$, which looks like this:

• $1, 2 3.5, \pi$ etc.
• $i, i^2, 0.3 + 9.5 i + 23 i^3$ and so on.

Gabriella439

{-# LANGUAGE ApplicativeDo               #-}
{-# LANGUAGE BlockArguments             #-}
{-# LANGUAGE DeriveFunctor              #-}
{-# LANGUAGE DerivingStrategies         #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE UndecidableInstances       #-}

module HasCal where

import Control.Applicative (Alternative(..), liftA2)

Gabriella439

# This was only tested against revision ac2d18a7353cd3ac1ba4b5993f2776fe0c5eedc9
# of https://gitlab.haskell.org/ghc/ghc
let
  nixpkgs = builtins.fetchTarball {
    url    = "https://github.com/NixOS/nixpkgs/archive/7e003d7fb9eff8ecb84405360c75c716cdd1f79f.tar.gz";
    sha256 = "08y8pmz7xa58mrk52nafgnnrryxsmya9qaab3nccg18jifs5gyal";
  };

  config.allowBroken = true;